Compounds for use in the treatment or prophylaxis of pain, including acute andchronic pain (e.g., nociceptivepain, neuropathic pain, headaches, migraine), represented by general formula(I) in which: the dotted line represents a single or adouble bond; and R5 and R5' are independently -H, -OH or -OR6, where R6 is alinear or branched C1-C4 alkyl; X is -0-, -CH2O-, -OCH2CH2O-, -CH(CH3)CH2O- or -CH2CH(CH3)O-; Z is -CH2CH2O-, -CH(CH3)CH2O- or -CH2CH(CH3)O-; m is an integer of 0 or1; and n is an integer of 0-50. The compounds of the invention are alsoeffective for reducing inflammation and may be used aloneor in combination with other analgesics.